Commit Message

Jimi Xenidis <jimix@pobox.com> wrote:
> Sorry for the pause, lots of other things getting done... questions below.> > On Nov 9, 2012, at 10:33 PM, Michael Neuling <mikey@neuling.org> wrote:> > > Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:> > > >> On Fri, 2012-11-09 at 11:43 -0600, Jimi Xenidis wrote:> >>> The CPU_FTR_* values are pretty tight (a few bits left) yes I need to save and restore the QPX registers.> >>> There are 32 QPX registers, each 32 bytes in size, it is otherwise managed by the FPSCR and MSR[FP]> >>> > >>> I was thinking that I could hijack the VSX, since there is no plan to add it to embedded yet.> >>> I could be explicit or create an alieas fo the same bit, but the basic effect (after increasing the save area size) would be something like the diff below.> >>> Thoughts?> >> > >> Don't. Use a different bit, we can always split the mask again if> >> needed, move more bits to mmu_features etc...> > Ok> > >> > >>> -#ifdef CONFIG_VSX> >>> +#if defined (CONFIG_VSX) && defined(CONFIG_BGQ)> >>> +# error "This code depends on CONFIG_VSX and CONFIG_BGQ being exclusive> >>> +#elif defined (CONFIG_VSX)> >>> +# define _REST_32VSRS(n,c,base) REST_32VSRS(n,c,base)> >>> +# define _SAVE_32VSRS(n,c,base) SAVE_32VSRS(n,c,base)> >>> +#elif defined(CONFIG_BGQ)> >> > >> Make a CONFIG_PPC_QPX or something like that specifically for the QPX> >> stuff that you can then "select" from CONFIG_PPC_BGQ (don't do just> >> CONFIG_BGQ).> > ack> > >> > >> And don't just "hijack" stuff like that, it should be a runtime option,> >> so add a new set etc... it should be possible to build a kernel that> >> boots on a BGQ or a hypothetical BookE chip with VSX.> > ack> > > > Yeah both bluegene and VSX are designed for HPC, so it's not completely> > crazy that someone would put them together.> > Not sure that is possible, since they both "include" FPU state, which> is why hijacking the the FPU routines is so delicious.
I have this patch in my tree to push upstream at some point. It packs
all the CPU_FTR_* bits so that we have a few free at the end.
Benh: How about we take this now (or whatever merges). Then we add a
the new bits we know we need in the near future like PPR, DOORBELLS, TM,
and JIMIS_VERY_CRAZY_BGQ_FPU?
Or, can we all just post random CPU_FTR bits and you'll (benh) fix the
merge issues?
Mikey
commit 35f9a3ed7065b80013df87e33a832537c2ce224e
Author: Michael Neuling <mikey@neuling.org>
Date: Fri Nov 30 16:40:56 2012 +1100
repack 64bit cpu features to remove holes